First off, look at the turbo. if the intake of the turbo has a bolted flange, then it is a GTR turbo. Next look at the exhaust manifold. If it has equal length pipes, it is a GTR manifold. Look inside the intake plenum. A GTR plenum has baffles in it. The baffles prevent the number one cylinder to over pressurize from the velocity of the air going inside the plenum, ramming to the rear of the plenum and going into the number 1 cylinder.
Those are the easist ways to tell them apart. If all else fails, take photos and let me check them out. How do I know? I have a GTR engine sitting in my garage under a bunch of crap.